The field of the invention pertains to cartridges and valves for the dispensing of highly viscous materials and, in particular, to valves that can be used to control and seal dispensers for such materials. The materials include common caulking, butyl and silicone sealants as well as a multitude of other materials dispensed from cartridges or caulking tubes inserted in caulking guns.
The typical caulking tube or cartridge type of dispenser comprises a cardboard tube with one metal end sealingly attached to the cardboard tube. A plastic nozzle, snout or applicator tip extends from the metal end. As manufactured and sold the applicator tip is sealed. An additional internal aluminized plastic seal covers the opening through the metal end into the cartridge tip. The other end of the tube includes an internally mounted diaphragm seal or cover that is engageable by the caulking gun plunger to apply pressure to the material in the tube and thereby expel the material through the applicator tip.
Before applying pressure to the diaphragm, the tapered end of the applicator tip is opened and trimmed by the user to provide the desired opening diameter and a nail or other sharp pointed object is inserted to pierce the aluminized plastic seal.
Unfortunately, once the tube or cartridge is opened, the applicator tip can not be properly closed or resealed in a manner that prevents air from entering and causing the material in the applicator tip to harden. Since the applicator tip is tapered, the slug of hardened material becomes difficult to expel. Typically, increased force applied to the plunger causes the cardboard to burst with the result that the material can no longer be properly dispensed from the cartridge.
A second problem with the applicator tip is that once trimmed to a large opening, the opening can no longer be reduced to a smaller cross section for a smaller bead.
A cap to cover the trimmed applicator tip can be applied as provided with some cartridges, however, the cap is removed in use and can easily be mislaid. The cap also permits air to be trapped at the tip thereby permitting hardening of material at the tip to ensue.
U.S. Pat. No. 2,859,932 illustrates a flexible plastic two part valve for inflating or deflating plastic toys. The valve may also be used for controlling the passage of liquids. The patent discloses various means for retaining the valve in a fully closed gas tight position as distinguished from the fully open position. As disclosed the valves are permanently attached as an integral part of the toy or other item with means to attach an air pump or vacuum pump.
With a view toward overcoming the problems noted above, the applicant has developed the valve disclosed and described below.